| 摘要 |
PURPOSE:To continue the operation of an inverter in an overload state while the decline of a load induction motor caused by the output frequency reducing control of the inverter is suppressed as little as possible. CONSTITUTION:The input current I1 of an inverter is detected by an input current detector 9 and the detected current is compared with a set current value for overload state detection by a chopper controller 10. If the overload state of the inverter is detected, an inverter output frequency and, at the same time, the terminal voltage V1 of a capacitor 6 are controlled to reduce following respectively specified time change rates in the ranges larger than the respective lower limits by an inverter driving circuit 11 and through the ON/OFF control of a chopper transistor 4 respectively to continue the operation of the inverter in the overload state. |
